Slide-rule.



Patented luly 2, 190|.

E. THACHER.

SLIDE RULE.

(Application led Feb. 27, 1900.)

(No Model.)

d/fornez/ :n: cams Perses co. PHOTO-urna, wAsHmr-mn UNITED STATES PATENT OFFICE.

EDWIN THAOHER, OF PATERSON, NEW JERSEY, ASSIGNOR OF ONE-HALF TO EDSON M. SOOFIELD, OF -YOUNGSTOWN, OHIO.

SLIDE-RULE.

srncrnronfriolv forming part of'neaers Patent No. 677,817, daten Jury 2, 1901.

Application filed February 2.7, 1900. Serial No. 6,717. (No model.)

T all whom t may concern;

Be it known that I, EDWNTHACHER, a

citizen of the United States, residing at Paterson, in the county of Passaic and State of i New Jersey, have invented certain new and useful Improvements in Slide-Rules; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to calculating logarithmic slide-rules, and has for its object a greater convenience in handling, a greater speed in a variety of calculations, and a greater range of useful calculations than can be found with any slide-rule now in the market. The logarithmic scales may be stamped or engraved on lthe rule or they may be printed on paper, Celluloid, or other material and attached to the side or sides' of the rule, as is thought most desirable in manufacture. The slide or slides admit of an-easy movement back and forth to the right or left between the iixed lines of the rule, so that any number or division on the slides may be brought opposite to or in contact with any desired number or division on the fixed lines, admitting of accurate and rapid setting or reading without the aid of a runner.

Figures 1 and 2 represent a slide-rule illustrative of my invention and showing the slide or slides partly drawn out to the left. Fig.

K 3 shows a section of the rule with two slides, vone on each sideof the rule, Fig. 1-or its equivalent occupying one side of the rule, and Fig. 2 or its equivalent the other side of the rule. Fig. 4 shows a section of the rule with one slide only. On this rule either Fig. 1 or Fig. 2 is used, the two being used independently or on different rules.

In Figs. l and 2, A, B, O, D, E, and F represent logarithmic scales-that is, scales in which the distance of any number from the beginning of the scale corresponds to the mantissa of the logarithm of that number. Such scales are laid oft in prime divisions from l to 10, eachprime division being subdivided as nely as desired and depending upon the length of the rule. For a twentytwo-inch rule I would prefer to have each prime division subdivided as follows: scales A, B, and O, from l to 5,iifty parts; from 5 to 10, ten parts; scales D, E, and F, from1 to 2, one hundred parts; from 2 to 5, fifty parts;` from 5 to 10, twenty parts. Some of these divisions are omitted from the drawings for the sake of clearness, the number and iineness of the subdivisions being optional with the manu--l arbitrary. Thus 2 on the scales may mean 'f two, twenty, two hundred, or .2, .02, .002, dto., as the nature of the problem to be solved may require. Such scales represent the logarithms of all numbers, the accuracy of the reading depending upon the length of scale employed and the number of its subdivisions. The manner of using such scales for making computations is well understood and need not here be described in detail. V

In Fig. 1 scales A, B, and O have a length equal to half the graduated length of the rule, scales A and Bvbeing laid off from left to right and scale O from right to left, as shown, the numbers on scale C being the reciprocals of the numbers opposite on scale B. Scales l B and C occupy the fixed lines on the left half of the'rule, and scale A occupies the entire slide, being laid off twice on each edge of slide, or four times altogether. Scale D is a scale of roots and has a length equal to the graduated length of the rule and isvdivided into rtwo parts of equal length. rl`vhe irst part gives all numbers from 1 to 10 and the second part all numbers from V10 to 10. These parts are laid off on the fixed lines of the right half of the rule, one at top and the other at bottom, thetwo roots of any number on the slide being opposite to each other on the xed lines. By this arrangement by moving-the slide to the left any number on scales A may be brought .opposite any required number ou scales B or C without moving the end of the slide-beyond the center possible number within the reading limits of such scales, and the resultsbe read without a resetting of the rule. By moving the slide to the right any number on scale A may be brought opposite any desired number on scale D without moving the slide beyond the center line of the rule, and when so set complete logarithmic scales A and D will be found in contact for direct comparison. then scales A and B or A and O are set in any desired position with respect to each other and a full scale D is then desired in Contact with a full scale A, the slide is moved to the right onehalf its length, or the length of scale A. Inorder to bring scale A into direct contact with scales B, O, and D, I prefer the arrangement shown in Fig. l; but it maybe accomplished by reversing the arrangement, the scales A being on the fixed lines and the scales B, O, and D on the slide.

In Fig. 2 scale F on the top fixed line is a complete and continuous scale occupying the graduated length of the rule,beginning on the left and ending on the right. On the bottom fixed line this scale begins and ends at the center of the rule, the first half of the scale occupying the right half of the rule and thel last halt' of the scale the left half of the rule,

l or l0 on the top fixed line being op- This i posite fs/lll on the bottom fixed line. gives a com plete scale on each half of the fixed lines of the rule to the right or left of theV F on top fixed line, and scale E on bottom edge of slide will match scale F on bottom fixed line, there being a complete scale E on each half of the slide to the right or left of the center. By moving the slide to the right or left any required number on scale E may be brought opposite any required number on scale F Without moving the end of the slide i `by the rules given.

beyond the center line of the rule, and when so set complete logarithmic scales E and F will be found in contact for direct comparison. Consequently the scales being set for an57 given ratio such ratio may be multiplied by any possible number within the reading limits of such scales and the results be read without a resetting of the rule. As scales E and F each have a length equal to the total graduated length of the rule and as the length ot' rule in all rules without a runner has heretofore been twice the length of scale, Fig. 2 gives without the aid of a runner a four-foot rule on a two-foot stick, resulting in much greater speed in operating than is possible with rules requiring a runner and `be set as often as their lvalue is changed. is not used in sett-ing and may have any num lber of values Without resetting. `ture is of great value in all prorata queslarge percentage of all calculations.

much greater accuracy of results than can be obtained with rules requiring no runner.

Fig. l shows an arrangement of scales or a rule adapted to the Working of the follow- Rule l: Opposite I) on iD, if second powerd set a on A. Then opposite .r on

B, it first poweigl D, if second power,

find answer on A.

and JI) a', slide direct. ll

t T i E@ and L7-g, slide reversed.)

B, if first power, t D, if second power,

Rule 2: Opposite I) on set a on A. Then opposite on A read answer on D.

c a no and c Ct fr?, slide direct. (3) Rule 3: Opposite c on O set a on A. Then y. f SB if `first powerd` opposite .c on ,D1 if Second power); Vind an siver on A.

5% and slide direct. (-1-) Rule 4: Opposite L on 5b 1f mst power? 2D, it second power( set Ct on A. Then opposite on C .find answer on A.

*af -4 l l l f /Gdsitetiiect (o) Rule 5: Opposite c on O set (ton A. Then opposite fc on A find answer on D.

The preceding formulas are readily solved In these formulas a, '1), and c may have any value; but the slide must This feations, stresses, sections, die.; in fact, a very The formulas are general. It, for example, in the `and if a and b have a value difterent from l it is proportion, and the same applies to all i other formulas.

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IICI

Fig. l shows the slide drawn out to the left, so that 2 on Ais opposite l on B, and a few examples in application of the rules will be given for the slide in this position:

.5 4 4.2= 320.0. i by RM@ 3' Fig. 2 shows a rule adapted to the working e a: of the general formula embracing all opformula@ (6) is worked by the following general rule:

Rule 6: Oppositefon F set e on E. Then opposite a: on F ind answer on E.

In the formula el is not used in setting and may have any number of values without resetting.

Fig. 2 shows the slide drawn out to the left, so that 2 on E is opposite l on F, and a few examples in application of Rule 6 will be given for the slide in this position:

xldao, (te.

What I claim as my invention, and wish to 'logarithmic scales relatively adjustable, one

of said scales formed of two parts, one above the other, having a combined length equal to the graduated length of the rule, substantially as described. Y

2. 'A slide-rule, comprising a plurality of logarithmic scales relatively adjustable, one of said scales formed of two equal parts, one above the other, having a combined length equal to the graduated length of the rule, and arranged upon one side of the transverse center of the rule, substantially as described.

3. A slide-rule, comprising a fixed and movable logarithmic scale arranged upon one side of the transverse center of the rule, said fixed scale being composed of two equal parts, one

above the other, having a combined length equal to the graduated length of the rule, and

said movable scale being formed of one part having a length equal to one-half the graduated length of the rule, and being laid off on each edge of the slide, substantially as deL scribed.

, 4.' A slide-rule, comprising iixed or movable l logarithmic scales as follows: a direct scale of roots composed of two equal parts arranged one above the other upon one side of the transverse center of the rule (whether base or slide) and having a combined length equal to the graduated length of the rule, in combination with a direct and a reversed scale of'squares each composed of one part having a length equal to one-half the graduated length of the rule and arranged upon the opposite side of the transverse center of the rule, the direct scales reading from left to right and the re# versed scale reading from right to left, substantially as described.

` 5. A sliderule, composed of base and slide members, bearing the following logarithmic scalesfviz: scale A upon each side of the transverse center of the slide, and upon each edge thereof, reading from left to right; scale B upon one side of the transverse center of the base, reading from left to right; scale C upon the same side of the transverse center of the base, reading from right to left; scale D ar*- .ranged in two equal parts, one above the other, upon the opposite side of the transL verse center of the base, reading from left to right; each of said scales A, B and C having a length equal to one half the graduated length of the rule,.and scale D having a combined length equal to the graduated length of the rule, substantially as described.

In testimony whereof I subscribe my signa-f ture in presence of two witnesses.

EDWIN THACIIEB..

Witnesses:

EDWARD F. MENEY, Woon MCKEE.

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